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Патент USA US3070174

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United States Patent Oil-"ice
Fatented Dec. 25, 19451.
ample, quantities of the treating agents may be alternately
pumped downwardly into the well along the same path,
such as through the tubing or through the annular space
Thomas .5. Gordon, .lr., Great Bend, Kane, assignor to
Halliburton Company, a corporation of Delaware
No Drawing. Filed Feb. 19, 196i),
No. 9,721
4 Claims. (U. 166—41)=
between the tubing and the surrounding surface in the
well. A well packer may advantageously be employed
This invention relates generally to the treating of oil
the treating agents or to facilitate the injection thereof
into the pores and other openings of the surrounding
in the well at one or both of the upper and lower limits
of the zone or formation to be treated, such as to con?ne
and gas wells or the like and, more particularly, to well
treating compositions containing acid and to methods 10 strata.
As in conventional acidizing procedures, the quantities
utilizing the same in treating or acidizing operations per
underground structure, such as a Zone or formation con~
of treating agents required for best results will vary wide
ly from well to well, depending on the particular condi
taining oil or gas.
tions encountered. in certain wells it may be necessary
formed to increase or restore the permeability of an
It is believed that the invention will be most widely 15 or desirable to repeat the treatment at relatively frequent
intervals, while in other wells repeated treatments may
applied in connection with treating or acidizing opera—
seldom, if ever, be necessary.
tions which are performed on zones or formations par
,As one example, a well in Kansas was treated using
tially or completely plugged with paraffin or scale de
200 gallons of hydrochloric acid solution followed by 200
posits, such as deposits containing iron sul?de, iron oxide,
calcium sulfate or the like. It is understood, however, 20 gallons of acetic anhydride which in turn was followed by
80!) gallons of hydrochloric acid solution, with each batch
that the invention may be applied elsewhere. In particu
being pumped downwardly into the well along the annular
lar, it is anticipated that the invention will provide ad
space surrounding the tubing. As another example, a
vantages in acidizing operations Where improved results
second well in Kansas was similarly treated using 400 gal
can be obtained if additional heat is present, that is,
lons of acetic anhydride spaced in 3,090 gallons of hy
where a “hot” acid is desired or needed.
drochloric acid solution.
Accordingly, a general object of the invention is to
In preparing the treating ?uids, various other additives
provide an improved well treating composition contain
and agents may be included, if desired. For example, an
ing acid and an improved method utilizing the same in
well treating or acidizing operations.
Another object of the invention is to provide an im
acid inhibitor may be included, such as in the stream or
portion thereof containing the hydrochloric acid. Also,
proved composition and method useful in well treating
or acidizing operations wherein it is desired to employ
an agent selected to improve the penetrability of the treat
a “hot” acid, such as in removing para?in or scale de
posits tending to obstruct the ?ow of ?uid in a zone or
formation penetrated by the bore of an oil or gas well or
both of the separate quantities prepared.
the like.
The foregoing and additional objects and advantages
are attained by the invention, which involves the general
ing ?uids into the well strata may be included in one or
if desired,
agents may be included to prevent or remove water and
emulsion blocks, and for other purposes.
While the invention is not limited to any particular
theory of behavior, it is believed that the superior results
obtained are due to a combination of advantages resultin
from the particular compositions and methods employed.
concept of improving an acidizing operation by generat
ing additional heat, preferably as nearly as possible to 10 For one thing, the introduction of the acetic anhydride
into the well substantially separated from the acid solution
the place of treatment, by reacting together a mineral acid
acid, which may be of the type commonly employed in
results in the development of considerable heat when
these ingredients eventually come together in the well
well acidizing operations, and an agent, such as acetic an
bore or in the adjacent well strata.
hydride, selected to produce heat upon reacting with the
acid solution.
In one way of proceeding, quantities of acetic anhy
gether at a desired location therein, such as opposite the
Where the treatment is performed in a well containing
paraf?n or scale deposits which are removed more easily
in the presence of heat, or by the application of heat in
addition to a solvent or treating agent, the development
of heat as nearly as possible to the location of the sub
stances to be dissolved or removed is believed to greatly
facilitate the treatment. By permitting a more efficient
face of an underground zone or formation to be treated.
utilization of the higher temperature ?uids existing early
solution, such as an aqueous solution of hydrochloric
dride and an aqueous solution of hydrochloric acid are
introduced, while substantially separated, into an oil or
gas well or the like and then are allowed to come to
For example, quantities of the acetic anhydride and acid
during the reaction which occurs upon the acetic anhy
solution may be separately prepared at the surface of a
well equipped with a tubing or the like which extends
dride and hydrochloric acid solution coming together, the
present invention provides greater effectiveness of treat
downwardly to the vicinity of a zone or formation to
be treated. The tubing and surrounding annular space
Also, it is believed that the acetic anhydride itself con
tributes to the acidizing of the well, since the product of
its reaction with the aqueous hydrochloric acid solution,
thus provide separate paths extending into the well. The
acetic anhydride and acid solution are separately intro
duced and conducted downwardly into the well, each fol
lowing its separate path until the two are allowed or
caused to meet at an interface in the well.
If desired, two liquid streams, each containing one. of
the treating agents, may be pumped downwardly into the
well along the separate paths and the pumping rates of the
two streams may be controlled or adjusted at intervals
during the treatment to control or adjust the location
of the interface at which the acetic anhydride and the
acid solution come together in the well.
In another way of proceeding, the acetic anhydride
and the acid solution are introduced into the well in sub
stantially separate parts of the same stream. For ex
or with water which may be otherwise present in the well,
is acetic acid which is known in the prior art as an acidiz—
ing ?uid the use of which aiiords advantages in
erations, such as in treating wells in which treatments
with hydrochloric
have not always been completely
While the invention has been described with reference
to certain particulars and details thereof, it is understood
that these are by way of example and that mod ations
within the spirit of the invention will now present them
70 selves to those skilled in the art. Accordingly, the inven
tion should not be considered limited except by the scope
of the claims appended hereto.
‘What is claimed is:
1. in a well treating operation performed to remove
para?in or scale deposits, the steps of introducing into the
well substantially separated treating ?uids one of which
contains hydrochloric acid and the other of which con
tains acetic anhydride, causing said treating ?uids to come
together and remain in the Well for a period of time,
whereby heat is produced as said mineral acid and acetic
anhydride react together during the course of treating the
well, and subsequently removing the treating fluids and
removed deposits from the well.
2. A method or" treating wells for removal of paraf?n
and scale deposits, comprising the steps of:
(a) introducing a quantity of acetic 'anhydride down
an annulus in a well bore;
(at) introducing a quantity of an aqueous solution of
hydrochloric acid into a well bore and to the area
to be treated;
(b) thereafter introducing a quantity of acetic an
hydride into the Well bore; and
(c) causing the acetic anhydride to contact the aqueous
‘solution of hydrochloric acid at the area to be treated
in the Well bore whereby a quantity of heat is pro
duced for removing paraffin and scale deposits there
4. The method of claim 3, wherein quantities of aque
ous solution of hydrochloric acid and quantities of acetic
anhydride are alternately introduced into the well at rela
tively frequent intervals for producing additional heat as
(b) substantially simultaneously therewith, introduc
ing a quantity of an aqueous solution of hydrochloric
acid down a separate annulus in the Well bore, where
by the acetic anhydride and the hydrochloric acid
References Cited in the ?le of this patent
to meet at a predetermined interface in the well,
thereby producing a substantial quantity of heat for
Perrine _______________ __ Dec. 9, 1958
removing para?n and scale deposits therefrom.
3. A method of treating wells for removal of para?in
and scale deposits, comprising the steps of:
Canada ______________ __ Feb. 3, 1959
are each separately introduced and conducted clown
wardly into the well; and
(c) causing the hydrochloric acid and acetic anhydride
Mills _______________ __ May
Hund et a]. _________ __ Nov.
Limerick et a1 _________ __ June
Frye et al. ___________ __ Feb.
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